In mid-May, the first reports of monkey pox cases in Europe began to surface. A week later, there were 92 confirmed cases outside the Central and West African countries where the disease usually circulates; now there are 1,200. Who knows by the end of this month? “If you had asked me two weeks ago, I would have expected that there might be a few thousand cases worldwide associated with this current outbreak,” Jay Varma, a public health professor at Weill Cornell Medical College, told me. † “But I’ve become much more pessimistic.”
Where exactly is the outbreak headed? When I asked five experts for their predictions, they only said one thing for sure: Monkeypox is not the next COVID-19. It’s just not transmissible enough to cause infections on the scale of the pandemic, nor does it appear to be a particularly deadly virus. (None of the 1,200 patients have died so far.) But otherwise, their views diverged widely: The outbreak may be over before we know it; or it may become a modest, intermittent problem; or it can turn into an ever-present risk and discomfort, such as the following genital herpes. Here are three possible paths Monkeypox could take.
The Rosy Scenario: A Quick Fizzle
This is not the first time monkeypox has entered the United States. At least 47 people in six states became sick with the virus in 2003 after interacting with infected prairie dogs as pets (legal to own in most states!). The spread was under control within a few months and no one died; two people became seriously ill, but recovered.
This time, prairie dogs are not involved. Most, if not all, cases of monkeypox in the US this year seem to have resulted from face-to-face contact. That makes the public health response more complicated than euthanizing potentially infected animals, as officials did in 2003. We could still quickly stop the spread through immunization, said Amesh Adalja, a senior scientist at the Johns Hopkins Center for Health. Security, me. After all, the US has a stash of smallpox vaccines on hand that would also work against this outbreak. (The exact size of the stock remains unclear.) “Monkeypox is a virus that can be controlled,” he told me.
The 2003 outbreak was caused in part by a tactic called ring vaccination, in which an infected patient’s close contacts are all vaccinated. This works because contact tracing for monkeypox is relatively easy thanks to the physical proximity required for its transmission, and because vaccinating someone who has recently been infected can prevent them from becoming contagious. Adalja predicts that ring vaccination will likely surpass the spread of monkeypox in the US within weeks, with the number of cases falling to zero in about three months.
The average scenario: a sporadic problem
Monkeypox is already breaking out occasionally in Central and West Africa. Experts say this is because the virus is endemic to local animal populations, likely some kind of mammal. The same could happen here in the US: If enough US wildlife becomes infected through interaction with infected humans, monkeypox could circulate silently after the number of human cases drops to zero. Every so often an animal would infect a person, that person would spread the virus to some close contacts, and another small outbreak would form, which then died out. Repeat indefinitely.
Bhargavi Rao, who worked in the Democratic Republic of the Congo and the Central African Republic as the head of emerging and infectious diseases at Doctors Without Borders, told me that a wave of monkeypox infections “isn’t something that overwhelms a community.” She said she thinks the risk of monkeypox becoming endemic in animals outside Central and West Africa is “very low,” but if it did, the effects would be similar to those of modern anthrax, rabies or bird flu; that is, it may cause occasional disturbance and lead to the occasional culling of animals, but it would generally not affect daily life. (James Diaz, director of environmental and occupational health at Louisiana State University, told me he suspects monkeypox is already endemic to U.S. wildlife, but also that there’s no hard evidence to support this claim.)
However, the fact that many recent cases have been registered in and around major cities can lead to different outcomes. In the countries where Rao worked, the disease usually spreads from wild animals to farmers and forest hunters living in isolated communities. She said there’s no way of knowing how big an outbreak could get in a US metropolis, even if those at risk generally have better access to tests and vaccines. If the outbreak were large enough, the virus could become endemic in rodent populations, triggering even more urban outbreaks in the future. “If it’s in the rats, you can’t do anything,” Adalja told me.
The Bad Scenario: Another Syphilis
We are dealing with something very different if the current outbreak cannot be stopped. Both Rao and Adalja said such a result seems unlikely, as monkeypox patients are generally not contagious before they are symptomatic, and the world already has tests, vaccines and treatments for the virus. But the conventional wisdom about monkey pox may not hold true for this outbreak. Varma, who helped lead New York City’s response to COVID, is far more concerned than the other experts I spoke to. “I’d say it’s less than a 50 percent chance we’ll contain this,” he said.
That’s not to say that a third of the country is likely to experience monkey pox in the next six months. Varma predicts that monkeypox will continue to circulate at low levels and remain concentrated in the community of men who have sex with men. (To be clear, monkeypox is not a sexually transmitted infection. The CDC has said that “a large number” of cases so far have involved men having sex with men, but the disease can be spread through sexual or non-sexual contact between Everyone.) If that’s what happens, then monkeypox would be similar to syphilis, said Varma, which affects about 0.04 percent of Americans, the most men who have sex with men. In Varma’s absolute worst-case scenario — which he thinks is less likely — monkeypox could spread through all kinds of communities, including children and pregnant women, and become as common as genital herpes, with more than 12 percent of Americans infected.
Again, this would not mean a collapse of civilization. Very few people who contract monkeypox die or become seriously ill. Even if monkeypox became widespread among the American population, Adalja told me, routine vaccination could eliminate many of the associated risks to people’s health. But the more people get sick, the greater the chance that someone will develop a rare and serious complication. Population-scale vaccination can also have drawbacks.
We also don’t know how the disease will change. DNA viruses, including monkeypox, are generally stable and evolve slowly into new strains. But “it’s never good to let a zoonotic virus spread unchecked in humans,” Boghuma Titanji, an infectious disease specialist at Emory University, told me. “The reality is you don’t know what the adaptation of that virus in a new host will do.” It can become more or less transmissible and cause more or less serious illness and death. Or it can stay pretty much the same.
No one will be able to accurately predict the future of this outbreak until we are sure of the present. And we’re just not there yet. The incubation period for the virus is one to two weeks on average, but can be as long as three, meaning the cases we see now reflect the spread of the virus many days ago. We’re also not testing enough to keep up with the outbreak, Titanji told me.
Testing is especially important because cases in the current outbreak look so different from classic monkeypox. Historically, monkeypox lesions developed first around the tongue and mouth, followed by a rash on the face, arms, and legs, which progressed to lesions; those symptoms were easy to see. However, the recent outbreak involved many patients with only a handful of lesions, concentrated around their genitals and anus. In the past, cases of monkey pox in the US were travel-related, and people who got sick came to travel clinics or told their doctors they were out of the country; now patients can turn up at sexual health clinics to examine the scabs on their genitals. The more accessible testing is, the easier it will be for patients to be identified and advised to isolate, while vaccines are provided to their contacts. “The sooner you can get a lab-confirmed infection, the sooner people take it seriously,” Varma said.
For now, we still don’t know how many people across the country are infected, nor how many others will eventually get sick. When I asked Titanji how and when we’ll know which path we’re on, she said it’s hard to tell and not worth guessing. “Any time a virus crosses a species and invades a new species, and it transmits itself and causes outbreaks, you are in a gray zone.”